Generally, industrial radiographic film is marketed in reels of long lengths of film, with the film being enveloped in a light-tight material. When radiographic film is wanted for use in thermal or nuclear electric power station constructions, a strip of radiographic film has to be cut to the length wanted in order to use it. The problem encountered is that part of the film around the cut is exposed to light. To avoid this problem, users of radiographic film fold the film and form two consecutive "U"s, and then wind the rounded part of each "U" using an adhesive. Thus each "U" has its two branches made solid. Then they cut the strip between the two "U"s. The problem encountered using this technique is that the strip of radiographic film is folded and can be damaged during this operation. Also, this operation is not always very convenient.